An mRNA maturase is encoded by the first intron of the mitochondrial gene for the subunit I of cytochrome oxidase in S. cerevisiae

Carignani, Giovanna; Groudinsky, Olga; Frezza, Domenico; Schiavon, E; Bergantino, Elisabetta; Słonimski, Piotr P.

doi:10.1016/0092-8674(83)90106-x

Cited by 169 publications

(64 citation statements)

References 35 publications

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“…For example, a cox1 mutant expressing both Pet309p and Mss51p but defective in intron aI1 splicing was shown to produce a 90-kDa protein translated from the continuous reading frame encoded by the first exon and part of the first intron of COX1. This protein is post-translationally cleaved into two polypeptides of 20 and 68 kDa, the latter constituting the maturase encoded by intron aI1 (Carignani et al, 1983). In contrast, synthesis of mp15 depends on the complete absence of Mss51p or presence of only limiting amounts of the translationally competent protein.…”

Section: Discussionmentioning

confidence: 99%

“…Because processing and translation of COX1 transcripts are interdependent events, splicing of some COX1 introns being dependent on translation of intron-encoded maturases (Carignani et al, 1983(Carignani et al, , 1986, mp15 is likely to be derived from an incompletely processed COX1 transcript. It was not excluded, however, that mp15 might be translated from an aberrantly spliced or partially degraded COX1 transcript.…”

Section: Synthesis Of Mp15 Is Affected By the Intron Composition Of Cox1mentioning

confidence: 99%

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Aberrant Translation of CytochromecOxidase Subunit 1 mRNA Species in the Absence of Mss51p in the YeastSaccharomyces cerevisiae

Zambrano

Fontanesi

Solans

et al. 2007

MBoC

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Expression of yeast mitochondrial genes depends on specific translational activators acting on the 5 -untranslated region of their target mRNAs. Mss51p is a translational factor for cytochrome c oxidase subunit 1 (COX1) mRNA and a key player in down-regulating Cox1p expression when subunits with which it normally interacts are not available. Mss51p probably acts on the 5 -untranslated region of COX1 mRNA to initiate translation and on the coding sequence itself to facilitate elongation. Mss51p binds newly synthesized Cox1p, an interaction that could be necessary for translation. To gain insight into the different roles of Mss51p on Cox1p biogenesis, we have analyzed the properties of a new mitochondrial protein, mp15, which is synthesized in mss51 mutants and in cytochrome oxidase mutants in which Cox1p translation is suppressed. The mp15 polypeptide is not detected in cox14 mutants that express Cox1p normally. We show that mp15 is a truncated translation product of COX1 mRNA whose synthesis requires the COX1 mRNA-specific translational activator Pet309p. These results support a key role for Mss51p in translationally regulating Cox1p synthesis by the status of cytochrome oxidase assembly.

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Section: Discussionmentioning

confidence: 99%

Section: Synthesis Of Mp15 Is Affected By the Intron Composition Of Cox1mentioning

confidence: 99%

Aberrant Translation of CytochromecOxidase Subunit 1 mRNA Species in the Absence of Mss51p in the YeastSaccharomyces cerevisiae

Zambrano

Fontanesi

Solans

et al. 2007

MBoC

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“…Nevertheless, the splicing reactions remain slower than in vivo, likely reflecting that additional, as yet unidentified, host proteins are needed for optimal RNA folding. The yeast aI1 and aI2 introns differ by encoding maturases, which stabilize their active structures (22,23). CYT-19 contributes to the splicing of these introns in vivo (12), but cannot by itself promote their splicing in vitro because the active structure is not sufficiently stable in the absence of the maturase.…”

Section: Discussionmentioning

confidence: 99%

A DEAD-box protein alone promotes group II intron splicing and reverse splicing by acting as an RNA chaperone

Mohr

Matsuura

Perlman

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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Group II intron RNAs self-splice in vitro but only at high salt and͞or Mg 2؉ concentrations and have been thought to require proteins to stabilize their active structure for efficient splicing in vivo. Here, we show that a DEAD-box protein, CYT-19, can by itself promote the splicing and reverse splicing of the yeast aI5␥ and bI1 group II introns under near-physiological conditions by acting as an ATPdependent RNA chaperone, whose continued presence is not required after RNA folding. Our results suggest that the folding of some group II introns may be limited by kinetic traps and that their active structures, once formed, do not require proteins or high Mg 2؉ concentrations for structural stabilization. Thus, during evolution, group II introns could have spliced and transposed by reverse splicing by using ubiquitous RNA chaperones before acquiring more specific protein partners to promote their splicing and mobility. More generally, our results provide additional evidence for the widespread role of RNA chaperones in folding cellular RNAs.catalytic RNA ͉ ribozyme ͉ RNA helicase ͉ RNA structure G roup II introns are mobile catalytic RNAs that splice via a lariat intermediate and may be ancestors of eukaryotic spliceosomal introns (1-3). To catalyze splicing, the intron RNAs fold into a conserved three-dimensional structure, which aligns the splice sites and branch-point nucleotide residue and uses bound Mg 2ϩ ions to activate the appropriate bonds for catalysis. The conserved three-dimensional structure of group II introns consists of six double-helical domains (D1 to D6), which interact with each other via tertiary contacts (3). Some group II introns self-splice in vitro, but only under nonphysiological conditions, including high monovalent salt and Mg 2ϩ concentrations, which were thought essential for RNA folding and structural stabilization. Thus far, most of what is known about group II intron RNA structure, folding, and reactivity has come from studies under such conditions (1-3).The efficient splicing of group II introns in vivo requires proteins to help the intron RNA fold into the catalytically active structure (reviewed in refs. 2-4). Mobile group II introns encode proteins, which have reverse transcriptase (RT) activity and also promote the splicing of the intron in which they are encoded (''maturase'' activity). Other group II introns do not encode maturases and instead rely on host proteins, which appear to differ in different organisms (2-4). Until now, a protein-dependent in vitro splicing system has been developed only for the RT͞maturase protein encoded by the mobile Lactococcus lactis Ll.LtrB intron (5, 6). Studies using this system showed that the maturase binds specifically to the intron RNA and promotes its splicing by stabilizing the catalytically active RNA structure (7,8).In addition to proteins that stabilize specific RNA structures, cellular RNAs may require RNA chaperones to disrupt stable inactive structure (''kinetic traps'') during RNA folding (9, 10). In the case of group I and II int...

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“…This folded RNA catalyzes RNA splicing via two transesterification reactions that are the same as those of spliceosomal introns in higher organisms and yield ligated exons and an excised intron lariat (Peebles et al 1986). For group II introns, the IEP, which is encoded in DIV, assists splicing by stabilizing the catalytically active RNA structure (Carignani et al 1983;Moran et al 1994;Matsuura et al 2001). It then remains bound to the excised intron lariat RNA in a ribonucleoprotein particle (RNP) that promotes intron mobility (Zimmerly et al 1995;Saldanha et al 1999).…”

Section: Introductionmentioning

confidence: 99%

Genetic identification of potential RNA-binding regions in a group II intron-encoded reverse transcriptase

Gu¹,

Cui²,

Mou³

et al. 2010

RNA

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Mobile group II introns encode a reverse transcriptase that binds the intron RNA to promote RNA splicing and intron mobility, the latter via reverse splicing of the excised intron into DNA sites, followed by reverse transcription. Previous work showed that the Lactococcus lactis Ll.LtrB intron reverse transcriptase, denoted LtrA protein, binds with high affinity to DIVa, a stem-loop structure at the beginning of the LtrA open reading frame and makes additional contacts with intron core regions that stabilize the active RNA structure for forward and reverse splicing. LtrA's binding to DIVa down-regulates its translation and is critical for initiation of reverse transcription. Here, by using high-throughput unigenic evolution analysis with a genetic assay in which LtrA binding to DIVa down-regulates translation of GFP, we identified regions at LtrA's N terminus that are required for DIVa binding. Then, by similar analysis with a reciprocal genetic assay, we confirmed that residual splicing of a mutant intron lacking DIVa does not require these N-terminal regions, but does require other reverse transcriptase (RT) and X/thumb domain regions that bind the intron core. We also show that N-terminal fragments of LtrA by themselves bind specifically to DIVa in vivo and in vitro. Our results suggest a model in which the N terminus of nascent LtrA binds DIVa of the intron RNA that encoded it and nucleates further interactions with core regions that promote RNP assembly for RNA splicing and intron mobility. Features of this model may be relevant to evolutionarily related non-long-terminal-repeat (non-LTR)-retrotransposon RTs.

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An mRNA maturase is encoded by the first intron of the mitochondrial gene for the subunit I of cytochrome oxidase in S. cerevisiae

Cited by 169 publications

References 35 publications

Aberrant Translation of CytochromecOxidase Subunit 1 mRNA Species in the Absence of Mss51p in the YeastSaccharomyces cerevisiae

Aberrant Translation of CytochromecOxidase Subunit 1 mRNA Species in the Absence of Mss51p in the YeastSaccharomyces cerevisiae

A DEAD-box protein alone promotes group II intron splicing and reverse splicing by acting as an RNA chaperone

Genetic identification of potential RNA-binding regions in a group II intron-encoded reverse transcriptase

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